The present invention relates to a data recording control system, and more particularly to an optical information recording and apparatus in which data is recorded with the optimum intensity of a laser beam irradiated on an optical recording medium.
Generally, in a magneto-optical type optical disk apparatus or the like, data is recorded through heating by a laser beam. However, there is the case where if a constant laser power is used, a recording operation becomes insufficient due to the dirtiness of a lens of an optical head, a change in environmental temperature of an optical disk medium, the variation of sensitivity of the optical disk medium or the like.
For example, in a magneto-optical disk apparatus, as the surface temperature of a magneto-optical disk recording medium raises due to a change thereof, a magnetic domain as recorded has a tendency to be enlarged. Therefore, it is necessary to reduce the power of a writing laser beam so that the magnetic domain is not enlarged. To the contrary, when the surface temperature of the medium is low, a magnetic domain as recorded has a tendency to be narrowed. Therefore, it is necessary to increase the power of the writing laser beam. Also, in the case where dust is deposited on an objective lens of an optical head or the disk surface, the laser power must be increased since it is hard for the laser power to reach the disk surface so that a magnetic domain is narrowed or not formed with the result that an error is liable to generate. A similar problem is also provided in a write-once type optical disk apparatus. Namely, when the temperature becomes high, excess heating takes place so that a pit is enlarged. Conversely, when the temperature becomes low, a pit is narrowed or not formed.
However, even if the change in temperature is encountered, it is difficult to measure the temperature of the medium surface directly. Then, there may be considered a method in which a temperature sensor is provided in the apparatus to control the power of a writing laser beam in accordance with a detected temperature. But, when a magneto-optical disk is newly mounted, a proper laser power control corresponding to a change in temperature of the magneto-optical disk is not possible since the temperature in the apparatus and the surface temperature of the magneto-optical disk are different from each other.
Thus, as shown in JP-A-4-67436, there is proposed a method in which the pre-write testing is performed on a predetermined area on an optical disk prior to data recording and a laser driving current intensity to optimize the power of a laser beam at the time of data recording is set on the basis of the result from reproducing of pre-write testing data.
In order to set the laser driving current at the time of data recording, a reproduced signal from pre-write testing data is required. Therefore, the pre-write testing necessitates both a recording operation and a reproducing operation. In the case where an optical head is of a one-beam type, the reproducing operation corresponds to a rotation subsequent to the recording operation. Accordingly, a time for processing of a write command is increased by a time length corresponding to at least one rotation. Further, in the case where an area for pre-write testing is allotted to an area on an optical disk apart from a user area, the increase of the processing time becomes large due to the movement of the optical head, the positioning thereof, and so forth. In the case where an optical head is of a two-beam type, the increase of the processing time caused by the pre-write testing is to the extent of one revolution of the optical disk, if a pre-write testing area is within a user sector. However, if the pre-write testing area is outside the user sector, an increase of the write command processing time is considerable.